1. Technical Field
The present disclosure relates to a communication apparatus mounted with a speech speed conversion device that receives a telephone call voice signal transmitted from a communication apparatus of a telephone call partner, converts a speech speed in a voice section of the voice signal, and outputs a resulting voice signal.
2. Description of the Related Art
A speech speed conversion device has, for example, a function of expanding the telephone call voice signal (that is, a voice signal on a voice reception side) transmitted from a telephone apparatus of a telephone call partner at a regular rate in a time direction and converting the telephone call voice signal into voice in which the telephone call partner speaks slowly and a listener easily listens.
In a speech speed conversion device disclosed in Japanese Patent No. 5346230, a voice section, in which an input signal includes voice, and a non-voice section, in which the input signal does not include voice, are determined, an expansion process is performed in a case where it is determined to be the voice section, and a compression process is performed in a case where it is determined to be the non-voice section. In addition, the speech speed conversion device does not perform the compression process in a case where a level of noise included in the input signal is equal to or higher than a prescribed threshold value even though it is determined to be the non-voice section. Therefore, it is possible for the speech speed conversion device to prevent output voice from being interrupted because the input voice is erroneously compressed.
However, speech speed conversion is performed in such a way that the input voice signal (input signal) is once accumulated in a signal memory and a past signal is read at a speed which is slow compared to the input signal.
In a case where the speech speed conversion device is mounted on a telephone with an automatic answering function and an automatic answering telephone message, which is accumulated as automatic answering, is reproduced at a slow speed, an idle capacity of the signal memory (voice buffer) of a speech speed convertor is ran out if the automatic answering telephone message is long. That is, in a case where the speech speed conversion is continued for a long time, delay between input and output increases, and thus the idle capacity of the signal memory is ran out.
As a result, the speech speed conversion is not performed until the idle capacity of the signal memory increases, and thus an advantage of the speech speed conversion is reduced. In this case, for example, a user listens to voice reception at a normal reproduction speed without performing the speech speed conversion from the middle, and thus the user becomes hard to listen and feels discomfort for a change in the voice speed of the voice reception. Particularly, in a case where the user listens to the automatic answering by voice, there may be a case in which the automatic answering voice is provided for a long time depending on an issue. Therefore, it is assumed that the idle capacity of the signal memory decreases, and thus the above situation is easily generated. In contrast, in a case where the capacity of the signal memory increases, the costs rise.